Resident Ahmad Ali told AFP that roughly two dozen assailants, who were "obviously Boko Haram fighters" stormed the village of Kwajaffa at dusk yesterday and ordered residents out of their homes.
Locals thought the Islamist insurgents "were going to preach and leave", but in fact they "opened fire on the crowd", Ali said.
Ali said the death toll likely passed two dozen but no other eye witnesses could be reached immediately to confirm the figures.
"They then went on setting fire to homes, burning half of the village before they left," he added.
Also Read
Details of attacks often take time to emerge, given the poor communications infrastructure in the embattled region.
Babagana Mustapha said a relative who fled the attack in Kwajaffa arrived at his home in southern Borno's commercial hub of Biu, 35 kilometres from Kwajaffa, yesterday.
This relative reported similar details concerning the attack, including a number of casualties, Mustapha told AFP.
Nigeria's military - backed by forces from Chad, Niger and Cameroon - has claimed huge victories over Boko Haram in the northeast over the last two months, retaking a series of towns and villages previously under rebel control.
The Islamist militants killed seven people going to a market in southern Chad on Friday, and then set improvised landmines on the road close to the Nigerian border.
Nigerian President Goodluck Jonathan's perceived mishandling of the Islamist insurgency was seen as a main reason for his overwhelming defeat in the northeast in last month's general elections.
Nigeria's president-elect Muhammadu Buhari will not take charge of the fight against Boko Haram until late May, but he has vowed to be a more effective commander-in-chief than Jonathan, in part by ensuring that the military is properly funded and equipped.